


Moth

by eloquated



Category: Hannibal (TV), Hannibal Lecter Series - All Media Types, Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Cannibalism, Dark Sherlock Holmes, M/M, Possessive Behavior, Unhealthy Relationships
Language: English
Status: Completed
Published: 2020-10-30
Updated: 2020-11-05
Packaged: 2021-03-09 01:09:06
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 7,542
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27286216
Author URL: https://archiveofourown.org/users/eloquated/pseuds/eloquated
Summary: Sherlock is four when he realizes his brother is fascinated by the dark, even when it scares him.It doesn't scare Sherlock.
Relationships: Mycroft Holmes/Hannibal Lecter, Mycroft Holmes/Sherlock Holmes
Comments: 36
Kudos: 48





	1. Chapter 1

**Notes for the Chapter:**

> [ sneaks back into the fandom after a long absence . ]
> 
> This isn't as dark as the tags make it sound, but I wanted to err on the side of caution, just in case!

"Sherlock, why are you skulking around at the foot of the stairs?"

The Holmes' living room flickered with the light from the television, everything washed in particularly lurid shades of red. It was the middle of the night, and Mycroft had turned the volume down so low that he had to strain to hear it. The dialogue was muddy, and he missed half the words; but he could make out the important bits.

And it was quiet enough that he'd heard the rustling of Sherlock's footie pajamas, and the way his breath snuffled, still congested from the cold he'd been fighting all week.

"I'm watching you. Mummy says you're not supposed to be watching scary movies! She says it's going to make you weird." Sherlock announced too loudly, one hand clutching his baby blanket, the soft drape of it trailing behind him. "Or  _ weirder _ ."

Mycroft thought there aught to be rules against being scolded by little brothers in frog pajamas.

"My sanity is quite firmly fixed in place, brother mine. Besides, I doubt even you would be scared by this movie." Silently, Mycroft gave himself a mental kick. He'd been so sure that Sherlock was asleep in bed, snuggled down with a humidifier and extra blankets. But he hadn't actually stopped to check. 

It was an unforgivable oversight, and one he didn't intend to repeat in the future.

However, the mistake sounded a great deal like an invitation, so Sherlock bounced over the back of the couch and wriggled into the space beside his brother. Mycroft was warm, and even his sigh was resigned to letting Sherlock stay. 

It was comfortable, safe. Wrapped in between Mycroft and his blanket, and it definitely didn't have anything to do with the very bloody man that had suddenly appeared on the screen.

Definitely not because of that at all.

And Sherlock definitely didn't hide his face in Mycroft's arm. 

After all, he was a pirate! Well, he was going to be a pirate for Halloween, which was in three days, and Sherlock was determined to live up to the part. 

"You're still not s'posed to be down here."

"Neither are you. And what Mummy doesn't know won't hurt her. But if you're going to talk through the whole film you can go back up to bed."

That was more than enough of a threat to lapse Sherlock into curious silence, for at least another ten minutes. "Why is this supposed to be scary? He's just  _ talking _ ." He whispered, trying for quiet and not coming anywhere close. "And why is she kissing him? Doesn't she know he chopped up all those people in the basement?"

Mycroft was fairly sure there were subjects you weren't supposed to address with your four-year-old brother. But banishing Sherlock back upstairs was just begging for him to fetch their parents. That would be inconvenient at best-- they'd be watching him more closely if they found out how often he crept downstairs to watch movies.

So after a pause, slowly chewing a few kernels of popcorn, mostly to buy time, Mycroft said, "She knows. But she thinks he's interesting, even when he's killing people."

Sherlock tilted his head, a fine furrow crossing his brow, "Well that's not very smart. Maybe he'll kill her, too! He probably will!"

Privately, Mycroft thought his little brother sounded a bit too gleeful about the idea of the fictional woman's inevitably gory demise. But since he'd been thinking the same thing, he chose not to comment. Instead, he shushed Sherlock, and resisted the urge to roll his eyes when his little brother installed himself under his arm.

"That's a very lot of blood! Is it supposed to spray like that?" Was his next question, a solid three minutes after the last one.

"If it's arterial blood, I believe it could. There are some rather large veins that supply the brain with blood and oxygen-- though, really, an adult body only holds about a gallon and a half of blood, so the  _ pooling _ on the floor is probably just for dramatic purposes."

Sherlock nodded sagely, and filed that bit of information away for later. He didn't quite understand 'dramatic purposes'. Wouldn't a horror movie be much scarier if it were more like life? More like something that could really happen?

He'd seen Frankenstein through the bars in the bannister the last time Mycroft had snuck downstairs, and that hadn't been scary at all! Just some squishy things in a lab, and some science that-- even at four-- Sherlock was sure wouldn't work. 

Dead things were dead, and they stayed that way. Just like the mouse he'd found outside in the grass, all the tiny organs on display where something had attacked it.

Sherlock had thought it was fascinating, all the little pieces spilling out of the abdominal cavity in bloody shades of grey and green. He'd poked at them with a twig, unspooling the intestines and prodding at the heart. At least, he'd thought it was the heart, it was the darkest organ, apart from the purplish one. 

That one was still a bit of a mystery.

The bodies on the screen now were mostly just red. Covered in red, like paint, and he couldn't understand why Mycroft had lapsed so quiet. Why he watched the man on the movie, dark haired and mouth smeared with blood-- 

And when had that happened? Had the man bitten himself? Had he bitten the girl?

Sherlock frowned against Mycroft's chest, and dragged his blanket up under his chin. He'd bitten Mycroft the week before, and his brother hadn't been very happy about it.

"It's not very scary." He muttered, lisping the protest around his thumb since Mycroft was too absorbed in the movie to stop him.

"It is, Sherlock. You just don't understand yet." 

Sherlock didn't agree, and anyway, watching Mycroft was more fun than watching the movie. His colour was up, flushed in the darkness until the red seemed to blur into his freckles. Just like he did when he was embarrassed, but Sherlock didn't think he was embarrassed now.

Not when it was just the two of them, and he didn't think Mummy or Daddy was going to wake up. 

There were goosebumps on Mycroft's arms, and that was even stranger, because it wasn't cold. And he barely blinked, staring at the screen like it held some sort of hypnotic power.

Sherlock didn't like not knowing. And he hated not knowing when it came to his brother. Mycroft was his constant, the one who explained and translated the world for him. Mycroft was eleven, and he knew things Sherlock didn't.

He'd probably know what that squishy purple bit of the mouse had been, but Sherlock hadn't asked, because he wanted to figure it out on his own.

"Then you should explain it!" He lisped, tongue curled against his thumb and the back of his front teeth.

"It's about the monster, Sherlock." Mycroft didn't shrug, because it would have dislodged his brother, who looked sullenly half asleep on the couch beside him. "He's interesting. I want to understand why he does all this."

"Because she's stupid. She doesn't understand that he owns her, so he has to show her."

"That's slavery, Sherlock. You can't own people."

"Yes you can. Maybe not le-ga-lly," He had to sound out the word, incongruously soft in his child's voice, "But I own you. You're mine. So you can too own people."

"I'm your brother, you mean. That's not quite the same thing." Mycroft looked down and smoothed his hand over Sherlock's unruly curls, letting them spring back under his fingers. He was such a strange child, made of willful defiance and mercurial curiousity, and he understood things like Mycroft did. Both of them were different from other children, but they had each other. "I still have my free will." 

Mycroft's smile died when Sherlock looked up at him, his eyes pale grey-blue in the dark. "No, you're mine. And I'm not going to share you."

Something cold slid down Mycroft's spine.


	2. Chapter 2

**Summary for the Chapter:**

> There had been six new murders in London in the last month, and Sherlock wanted to know every bloody detail. 

**Notes for the Chapter:**

> Happy Halloween everyone! I was going to update this later this week, but really? Celebrating Halloween with some dark Sherlock just seems right!

"Mycroft, haven't we talked about doing work in the evenings?"

"Hm? Oh, of course... I'm sorry, Hannibal. They practically threw it at me as I was leaving the office, and I was hoping to get some idea of what madness I'd be contending with in the morning."

"One day I'll get you into the kitchen with me. You can tell a lot about a person from what they make."

"Chaos, mostly, I'm afraid. Despite my best efforts, I've never had much luck with cooking."

"I'm sure we can change that. You just need the right teacher... Now, taste."

"Well, on your own head be it-- oh, that is very nice... What is it?"

"A sauce of red currant and lingonberry to accompany the loin."

"It's delicious, I've never had lingonberry before."

"No? It's a particular favourite of mine. And it does stain your mouth the most enticing red..."

...

There had been six new murders in London in the last month, and Sherlock wanted to know every bloody detail. 

He's sixteen and excited right down to the marrow of his bones, buzzing and excited with a mystery that even the Met can't solve(not that he has much faith in their abilities, but they should be able to find one murderer. It is their job after all!)

This isn't some Jack the Ripper copycat, slashing up bodies and leaving them to rot in back alleys and abandoned buildings. And it's not someone cutting throats and tossing the bodies into the Thames-- because there's nothing really exciting about that. Just gangs and infighting, and stupidity. 

No, this is an artist, someone taking their time, and selecting their trophies. The general public isn't supposed to know that little detail, because it screams serial killer; and those two words are a recipe for widespread panic. 

Sherlock is smart enough to know how counterproductive that would be. They'll never find the killer if people are running around like idiot chickens with their heads cut off. 

He doesn't have any faith that they're using their heads, or the brains inside them, but Sherlock wants to know how the story ends. How the mystery unravels. And eventually he's going to be the person pulling the strings to draw back the curtain.

The killer has left the bodies arranted, like exhibits in a museum. Two lovers, their hearts transposed into one another's chests, and a few little tidbits removed from each. Probably still with the killer, which amuses Sherlock to no end. 

Surrounded by a profusion of flowers, the bodies read like a love letter. A bit of grandstanding, showing off, because this killer clearly enjoys his work. 

Sherlock thinks he would keep killing, keep honing his craft (already the last set of bodies was more cleanly arranged than the first two), even without the person he's sending these love letters to. It's not a compulsion, it's a hobby.

Mummy thinks it's vile, and macabre, and Sherlock doesn't really care what she thinks. She's never been as smart as she thinks she is, and this isn't a problem of math. It's blood spilling across velvety petals; and missing lungs, and loin, a section of ribs, and the neck meat, all hidden in the profusion of sweet smelling flowers.

Technically Sherlock is supposed to be in Cambridge, studying. Preparing for exams, and finishing his current experiment, and not skulking through London like he's trying to lure out the killer by turning himself into bait.

Sherlock knows better; this killer has a taste for lovers. And he's very single, rattling around his dorm room, and the university, and generally eschewing human contact because they're so bloody annoying.

His parents will probably worry when they find out, but what they don't know won't hurt them.

Which is how he ended up in London in the middle of the afternoon, scurrying across Hampstead Heath on his way to the underground station on the other side of the park. He'd prefer to take a cab from one crime scene to another, but his wallet is a bit too light for that.

"Sherlock? What on Earth are you doing here?"

Mycroft's voice cut neatly through Sherlock's focus, scattering the bits of his deductions on the ground like crumbs. "What do you think I'm doing, Mycroft? I'm here to investiga...te... Who are  _ you? _ "

With a belated snap, Sherlock crossed his arms over his skinny chest and glared down at the figure sitting beside his big brother on an incongruously fine quality picnic blanket. And since when did Mycroft eat outside? 

The man was tall, probably even taller than Mycroft, though it was hard to tell sitting down. He was was dark haired, and well dressed, a little older than the Holmes brothers--

And his hand was resting at the small of Mycroft's back like it belonged there.

Sherlock disagreed.

In fact, he disagreed with the entire concept of people touching his brother. HIS brother. The emphasis was important there. Mycroft was his. He'd always been his, even when Sherlock hadn't been entirely sure he wanted him anymore. 

Mycroft had tried to abandon him when he'd left for university, but that hadn't changed anything. Especially now that Sherlock was attending Cambridge as well, and could see with his own two eyes that his brother hadn't left him for something better. 

More like a necessary evil.

"Be nice," Mycroft admonished, and turned to the man on the blanket with a faint, not particularly believable smile. "Hannibal, this is Sherlock, my little brother. And Sherlock, this is Hannibal Lecter, a friend of mine."

He wasn't a friend. And when Sherlock took a grudging half step forward to shake the man's outstretched hand, he could see the shadow of something dark and bruised half hidden under Mycroft's collar. 

Jealousy burned and sparked like lightning in his chest, and Sherlock didn't think he'd ever hated someone so much in all his life. This man was intruding where he didn't belong, putting his hands on Sherlock's toy brother, and leaving marks on him.

It wouldn't be so bad, he thought meanly, if his mystery killer got their hands on Hannibal Lecter.

"It's nice to finally have a face for the name. Mycroft talks about you frequently." Hannibal shook his hand warmly, and fixed Sherlock with a smile that reminded him of a shark. 

A smiling, amiable shark that would ask what sort of flowers you wanted at your funeral, right before they consumed you. 

"I have an idea... Why doesn't your brother join us for dinner?" 

Mycroft blinked in surprise, and Sherlock noted the way his brother leaned into Hannibal's space instinctively, drawn in by the man's hateful magnetism. "I'm not sure that's a good idea. My brother's manners leave something to be desired."

His pupils were too large, too dark, Sherlock noted. A physiological response to fear, and arousal, and neither of those options made any sense. But he pinned the thought to the inside of his mind to be examined later. It was just poor logic to be distracted when a shark invited you to dinner.

"Don't you want me to meet your family?"

"No-- I mean, yes, of course. If you're sure."

Hannibal's hand had migrated to the nape of Mycroft's neck, and Sherlock wanted to break every single finger. Slowly. With a hammer. Until all those long, slender bones splintered under the skin and pressed through to the surface, like a constant reminder not to touch Sherlock's things.

Mycroft tugged his sleeves straight, two points of livid colour high on his cheeks as he tilted his face up to look at Sherlock, "You remember where I live, brother mine?"

"In that pretentious little hidey hole you just bought in Mayfair, unless you've moved again."

"No, that's the right place. We'll see you tonight?"

Sherlock grinned toothily, and nodded, "I'll be there at six."

There was a mystery here, he could feel it. It reminded him a little of being small, and the way Mycroft would watch the monsters on television, wide eyed and barely breathing. Maybe half hard under the blanket across his lap, but Sherlock hadn't been able to see, so that was only his educated theory.

His big brother, the moth drawn to things that would burn him.

As it turned out, the well-dressed shark was, in fact, a very good cook. Even Sherlock, who had never taken much interest in food, beyond the usefulness of not dying, cleaned every plate put in front of him.

They talked about nothing in particular-- Mycroft's work, and Sherlock's studies, and the fact that Hannibal was a surgical resident at King's for the semester. His voice was shot through with an accent, like Latvian or Lithuanian, maybe Russian, that made all the words sound more interesting. Sherlock discovered that he liked to listen to him speak.

They debated history versus creative license, and the shifting of human morality. Of manners (which Sherlock was using) and what sort of rudeness was acceptable as a societal norm, and what was not.

Mycroft lapsed quiet, unhappy, when the conversation turned to the recent spate of murders; but Hannibal seemed bemused by Sherlock's observations and theories. 

The conversation lasted through a salad of bitter greens and a rich, oily dressing that looked a little odd, and tasted divine. A generous bowl of pappardelle, with tiny, hand-rolled meatballs that tasted vaguely sweet beneath the spices and marinade-- Sherlock would have thought pork, but it wasn't quite the same.

Rabbit, maybe?

"It's good."

"The secret is in the meat. Most people use sub-par cuts for meatballs, but I prefer using a mixture of neck meat and rib. The fattiness makes them more tender."

And finally, the three of them decamped to Mycroft's living room to enjoy tiny, delicate petit fours and black coffee for dessert.

Three minutes later, Mycroft's head lolled against Hannibal's shoulder, and the shark smile returned.

"You drugged him." Sherlock stated, watching the rise and fall of Mycroft's chest to make sure he was only sleeping. 

Hannibal barely nodded, just a faint incline of his sleek, dark head. He caught Mycroft's coffee cup deftly and set it on the table, like he'd been expecting it to fall. Sherlock was fairly sure he had.

Clearly, he'd done this before.

"It was the only way we'd be able to speak alone. Don't you agree?"

There was no point confirming it, so Sherlock set down his untouched cup, and leaned back in the overstuffed armchair that some interior designer had picked out when Mycroft bought the house. 

If Hannibal had put sedatives in Mycroft's coffee, Sherlock didn't plan to take any reckless chances. Even when Hannibal took a sip from his own cup, and hummed, clearly approving of the taste.

"Does he know what you are?"

Sherlock wasn't entirely sure when the thought had come to him, the little clues and facts aligning in his mind to form a cohesive image.

The flowers on the side table.

The meatballs.

The way Mycroft watched him just a bit too closely. 

And when Hannibal's mouth quirked up, Sherlock knew he was right. 

The light caught like sparks of red in Hannibal's maroon eyes, delighted by the question. "He's intrigued by me. And what I do. What I'm capable of."

Which Sherlock took to mean,  _ Yes, he does _ . And he would be right.

"You're not going to kill him."

Hannibal cocked his head and paused a beat, one eyebrow arched in silent query, "Why not?"

They stared at one another in the stillness of the living room, Mycroft's body slumped against Hannibal's side. 

Leaning over, Sherlock could see the bruise purple and red marks on his brother's throat, and he slotted his fingers along the paths Hannibal had left. He could feel Mycroft's pulse under his ring finger, fluttering just beneath the skin.

Mycroft was limp as a rag doll when Sherlock cupped his cheek, and pressed his thumb to his lips. It was so yielding, Sherlock could feel the warm wetness of his mouth as he pushed inside, mapping the ridge of his teeth and tongue.

Hannibal looked smug, because nobody had ever had to whisper through Sherlock Holmes' cocoon. He hadn't been fashioned this way, or manipulated into this curiousity... It was simply part of his nature. 

Sherlock chose to ignore his smirk.

"Because he's not yours to kill. He's mine. And he's always been mine."


	3. Chapter 3

**Summary for the Chapter:**

> Sherlock knew the path to Mycroft's room by touch memory, and he could find it even if he was blind drunk and high out of his mind.

**Notes for the Chapter:**

> I just wanted to say a quick thanks to everyone that's commented, your support of this little story has been wonderful! ❤

Sherlock's brain was buzzing, sparking, like lightning in his skull. 

The cocaine was quicksilver in his blood, staving off the worst of the boredom that had returned with a biting vengeance. 

It always did when there were no cases. No mysteries. Nothing to feed his brain but the endless minutiae of being human. 

It felt like it was eating itself, and so he turned to the cocaine for clarity.

Sherlock loved London, but sometimes he felt like the walls were closing in, and it was going to collapse on him.  _ London Bridge is falling down, falling down, falling down... my fair lady... _

He was only half aware that he was singing the nursery rhyme aloud, quiet and shot dark and strange in his deep voice. The cocaine helped him think, but Sherlock had nothing to think about; the world was dull, and creeping, and he was going to suffocate on the emptiness of it all.

The drugs helped. But only a little.

_ Build it up with silver and gold _

_ Silver and gold, silver and gold. _

Picking the locks on Mycroft's pretentious Mayfair house, and disabling his security system? That was an occupation for about five minutes. It would have been faster, but his hands were shaking inside his gloves, and London was never supposed to be this cold in October.

With a lurching stumble, Sherlock tumbled through the front door, both arms extended for balance. He caught himself on the entryway walls, leaving greasy, wet handprints on the wood paneling. 

_ Silver and gold will be stolen away _

_ Stolen away, stolen away. _

Mycroft was going to be annoyed when he saw that, and the thought made Sherlock grin meanly.

Sherlock knew the path to Mycroft's room by touch memory, and he could find it even if he was blind drunk and high out of his mind. He tugged off his gloves with his teeth, and tried not to analyze the bitterness on the fingers-- he wasn't sure what he'd touched, somewhere between Montague Street and Mayfair, but if he got sick?

That was tomorrow's problem.

Tonight's problem was fast asleep in bed, unaware that his house had been invaded.

_ Send a man to watch all night _

_ My fair lady. _

Mycroft kept his room dark, the windows covered in heavy drapes to keep out the ambient glow of London. He spent too much time traveling for work, hopping through time zones and trying to make up the sleep deficit when he got back home. 

But Sherlock loved the light, the incandescence, and the living neon brightness of the unsleeping city. So he threw open the curtains and delighted in the way the soft yellow light slanted through the mist on the window, and landed on Mycroft's face.

In the delicate spaces between his freckles, Mycroft was paler than Sherlock-- a porcelain whiteness from never seeing the sun. Sherlock could still vividly remember the mottled pattern of bruises that Hannibal Lecter had left behind. They'd lingered for weeks after he returned to America. 

He and Hannibal had been at an impasse, and retreat had been better for both of them.

In the stillness of the bedroom, Sherlock closed his fingers over his brother's throat, feeling for the delicate, sleep-slowed pulse. The muscles around his carotid tightened for an instant, as they always did-- some instinctive part of Mycroft flinching away from the ghoul that hovered over his bed.

"If I was anyone else, big brother, you would have been awake before I even got inside." 

Sherlock was never entirely sure if his brother was truly asleep, or simply laying still. Waiting to see what he would do. He supposed it didn't really matter, and deducing it would take something away from their game.

His fingers curled, and Mycroft stirred with a thick gasp.

"There we go, welcome back." Sherlock hummed as Mycroft blinked up at him in the dark. The night had bleached all the colour from their shared blue eyes, grey looking into grey. 

Sherlock searching for panic, and fear. He didn't find it.

And Mycroft wondered if this time-- because it wasn't the first, not even close-- his brother was going to push too hard. He'd learned better than to struggle, even when the black spots swarmed in front of his vision. He had a few choice scars to remind himself.

He didn't keep sharp things in his room anymore.

"Don't look at me like that, I'm not hurting you. You're just a little lightheaded, and that never killed anyone." 

Sherlock's fingers tightened, and Mycroft's stomach tugged hard and intense under the blankets, a dizzy heat flushing through his veins. This was madness, and Sherlock shouldn't even be here-- he was supposed to be in rehab, but Mycroft isn't that surprised to see him.

They aren't called Danger Nights because Sherlock is a threat to himself.

And it wasn't the first rehab facility he's talked his way out of. They can't hold him, and it always ends this way. With a midnight visit, and Sherlock's eyes blown wide and black in the dark.

He wants to see the way people work. He wants to dissect them, to lay their long muscles and tendons out so he can compare lengths. Eye colours. The shape of finger bones, and the tiny calcified areas where breaks have healed.

Sherlock craves clarity, like holding their brains in his hands will impart some of their wisdom on to him.

He hasn't killed, Mycroft would know if he had. He'd have to be the one to hide the body and make the police look the other way. 

Mycroft has a Yardie in mind for when the day comes. Lestrade is upstanding and loyal, and he'll do a credible job of finding the wrong answers Mycroft will leave for him.

For the moment, Sherlock's experiments are confined to the morgue at Bart's. But they both know it's only a matter of time before he loses interest in the dead. They don't blush, or scream; and they can't tell him where it hurts, and why.

Like the mouse when he was four, and the dog when he was twelve, he'll learn everything he can from these cadavers. And then he'll move on to something new.

Most of the time he doesn't want to kill Mycroft, because that would make the world dull. More dull. Mycroft is his to protect, or to end; and right now he likes him alive. He claimed his brother's life before he'd even started school:

His Mycroft. His brother. His. 

But he presses down against his throat, and Mycroft's eyes turn glassy from the hypoxia, brain slowing as he gasps for air. He can't speak, so Sherlock talks for them both.

"You're pretty like this. What would your colleagues say if they saw you now?" He leaned down, finding Mycroft's mouth with his thumb, and scraped the pinkness of it with his nail until it reddened. "I won't leave any marks, even though I want to. You let Hannibal do it, why not me?"

It had been a point of contention for years. Mycroft had let another man touch him, and Hannibal leaving for America had robbed Sherlock of his revenge. For now.

Mycroft tried to shake his head, something flickering under the lack of oxygen that looked a bit like fear.

"Because you're the great and powerful British Government now, right? You have an image to maintain, and people know you're not dating anyone. So bruises and hickeys would mean opening yourself to questions you don't want to answer."

Shuddering under him, Mycroft reached for Sherlock's wrist, but his fingers were growing clumsy, and he didn't have the leverage to move him. His eyes widened, dizziness bleeding into euphoria. 

He was asphyxiating, fumbling for Sherlock's hand. But his brother only leaned down--

And kissed him.

Mycroft tried to shake his head, but the world was blurring and Sherlock's mouth was hard and demanding, slanted over his own like he could steal the last of his breath. It wasn't supposed to be like this-- Mycroft had hidden this from Sherlock for a reason.

There were lines they couldn't cross, and his brother was crashing through them all, leaving only devastation and ruin in his path.

With his free hand, Sherlock pressed hard on the hinge of Mycroft's jaw, demanding it open to him. It was like being devoured, and they could both taste the copper of Mycroft's blood from a minute cut at the corner of his mouth. 

"You could keep me out. Change your alarms and hire a bodyguard. But you're not going to do that, are you? Or you could send me away again-- that was a nasty trick this time, big brother. I'm not going to fall for that twice." 

When he finally released his brother's throat, Mycroft jolted half upright, and choked on nothing as he desperately tried to pull in more air. Sherlock liked the way his throat moved, catching reflexively when breathing wasn't enough. His flushed cheeks matched the red handprints Sherlock had left, but they wouldn't last long.

There were rules about this sort of thing. 

And sometimes Sherlock listened to them. When it suited him.

"What the Hell do you think you're playing it?" Mycroft coughed, every syllable sounding sore, "You could have--"

"You're hard. So you couldn't have hated it that much."

"I can't be held accountable for every inconvenient erection, Sherlock. They're involuntary."

In the dark, Sherlock grinned down at him, a shadow figure with bright white teeth. He kicked off his boots, (another concession, part of the rules. Mycroft didn't want him tracking mud and all the filthy bits of London into the house. And certainly not into his bed.) and slid down beside him, brushing kisses along his brother's throat.

"Lock, stop. This has got to stop." But Mycroft only pulled the blanket aside to make room for his brother beside him. Sherlock was a monster, his monster.

But he was captivating-- he was beautiful, and Mycroft had always indulged him too much.

"If you were dead, I'd preserve you." Sherlock sprawled on his back, hands raised to paint pictures in the air. He had chipped polish on a few fingers, and Mycroft didn't ask why, or where it had come from. "With formalin and zinc salts, just like they used to. You're such a traditionalist, I think you'd like that more than modern formaldehyde embalming solution."

"You can't keep a body, even a preserved one, in your apartment." A dozen times in his life, Mycroft had felt the slithering coldness down his spine. His throat still burned, but his wits were slowly returning from their asphyxiated hiding place. 

Sherlock curled onto his side, and there was no mistaking the rigid press of his arousal against Mycroft's thigh. "Is that what you want, big brother? To be safe from me, locked up underground in some theft-proof coffin?" He sounded amused, mocking. "Something with locks, and chains. Or welded shut, so I'd need an oxy acetylene torch to get you back."

"I'd prefer to be alive, if it's all the same to you."

Sherlock never tried grave robbing... But how hard could it be? "I don't think you do. Otherwise you'd have gotten rid of me. You'd have taken advantage of one of your lucid moments, where you forget you're mine. And you'd have killed me."

"Don't be ridiculous, you're my brother. I wouldn't let anything happen to you. And I certainly wouldn't do it myself!"

"You would have stopped me from kissing you."

Mycroft's stomach twisted sickly, eyes fixed on the slanted light across the ceiling, "You shouldn't have done that, no."

"But you wanted me to." Sherlock propped himself on his elbow and looked down at his brother, toying with a few of his sleep-loose ginger curls. "I tell you I'm going to embalm you, and leave you in my bed-- and you cite legal technicalities. At least if you're dead, you can't want me anymore, isn't that the truth?"

Beneath his pajamas, Mycroft's skin prickled with goosebumps. "That's enough. You have your own bed, Sherlock. Go sleep in it."

"I don't want my bed. I want yours."

"Fine. Then I'll move."

For half a second, mostly delusional, Mycroft actually thought he'd be allowed to leave. 

Then Sherlock's arm locked around his waist, and dragged him back against his chest. "You'll stay. And we'll find out if being fucked by your little brother really is worse than death. It's an experiment, Mycie, do keep up."

"Stop it, Sherlock. Just stop it! I don't know what kind of game you're playing at, but--"

His fingers were like ice as they burrowed under his pajamas, searching out warm skin, and Mycroft's whole body seized with a shudder.

"You have to hold still, or this isn't going to be very nice. How long has it been since someone fucked you, Mycie? Too long? Or have you been whoring around with people I don't know about?"

Sherlock found the rigid length of his cock, and squeezed. 

Mycroft's protest twisted and caught in his throat, clotted with shame. It didn't matter than he could feel Sherlock rutting lazily against him from behind, or the heavy warmth of his breath on the back of his neck. He was the older brother, he was supposed to take care of Sherlock.

Not like this. Not ever like this.

"All this misplaced guild, I can feel how tense you are. Maybe you're afraid I'm armed? I won't hurt you like that again, Mycie..." He rolled his hips and delighted in the violent shiver that shot down Mycroft's spine, reverberating against his chest where their bodies pressed together.

"Don't worry, I'm going to take good care of you. We'll bleed off some of this tension you're carrying." Sherlock smirked against his neck, "Maybe that was a poor choice of words?"

"Sherlock, please..."

"Don't be tiresome, big brother. We both want this. We've wanted it since I was old enough to know what my prick was for. And you're not exactly pushing me away."

Mycroft shifted, pulled against his grip, and Sherlock's arm tightened around him. 

"This isn't... I don't want this. Whatever you might have convinced yourself-- I don't."

"Would you like it better if I held your throat again, Mycie? Then you could pretend that I was taking you by force. No need for guilt if you're not a consenting participant." 

"Stop it, just stop this!" Mycroft's voice pitched up an octave, thin and strained. He hated the sound of it, the defeat. Because Sherlock's wasn't wrong... 

When it came to each other, they were almost never wrong. 

Sherlock paused half a beat, and Mycroft could feel the metronome beat of his heart between his shoulder blades. 

He could feel the moment his grip relaxed, and Sherlock twisted forward to straddle his waist, the blankets and sheets and coat tangled around his knees.

"Mycie... My Mycie."

Sherlock leaned down to kiss him again, but it was softer this time, no teeth. And for all his protests and excuses, Mycroft opened for him, yielding under the searching pressure of his mouth.

"I'm not going to hurt you. I'll even forgive you for sending me away to rehab, instead of helping me yourself. I know you're scared." Sherlock smoothed his fingers over his brother's cheeks tenderly, like he was something precious. "And I still love you. Did you forget?"

He had.

Somewhere in the blood, and the drugs, and Mycroft leaving for university, he'd forgotten his little brother's love. 

Forgotten the way Sherlock clung to him, and the heavy, warm weight of his body when he slept. 

"I'm sorry, Lockie." He murmured, and let his brother rest their foreheads together, breathing in the same air.

"You still love me too?"

"Of course. Always."

Sherlock smiled against his mouth, and slid his hands over the planes of Mycroft's chest, searching for the buttons on his pajamas. "I'll remind you if you forget again. Where do you belong?"

This time it was Mycroft who smiled.

"We belong together."

"Always."


	4. Chapter 4

**Summary for the Chapter:**

> Holidays were an endless cyclical parade of birthdays and Valentines, and anniversaries. Trading presents and trite well-wishes to each other, and pretending to be something else.

**Notes for the Chapter:**

> And here we are on the last chapter! 
> 
> Though this dark Myc and Lock might appear again sometime... They're an awful lot of fun to write!

"Happy Anniversary, Mycroft."

The Holmes brothers had never made a habit of acknowledging date milestones-- it all seemed a little silly, not to mention arbitrary. Their relationship had a start date only in the most technical of terms

They might as well celebrate it as Sherlock's birthday, since that was the day they'd met. It made as much sense as the middle of October, when the parameters of their relationship had spilled over into something new.

Holidays were an endless cyclical parade of birthdays and Valentines, and anniversaries. Trading presents and trite well-wishes to each other, and pretending to be...

Well, anything other than what they were. 

But it technically wasn't a rule. If it had been, Sherlock would have contrarily broken it years before. It was simply an unspoken accord, something neither of them had really thought about much.

This year it was mostly an excuse for Mycroft to get him something nice. Ten years was a very long time, after all. 

"Brother mine... All finished with your new pet?"

Mycroft's home office was more of a nod to tradition than a proper work space; a snug, wood paneled space with part of his extensive library spanning two of the walls. Most of his important papers and things would be elsewhere, so Sherlock didn't feel the tiniest shred of guilt when he swept the pages off the top and planted himself in front of his brother.

Square in the middle of the desk as if to say,  _ That work was boring, you have a new subject to study now. Me. _

He wouldn't have bothered to feel guilty anywhere else, either. If Mycroft didn't want his paperwork scattered across the fine Persian rug, then he shouldn't have left them all over the desktop.

Honestly, it was just begging for someone to make a mess of it.

"Don't be jealous, Mycroft, you know you're mine. I'm not replacing you with a goldfish, no matter how good a shot he is."

Behind his desk, Mycroft rolled his blue eyes in long suffering affection, and rested his hands on his brother's thighs casually. As if the man sprawled on his desk with bedroom eyes was simply his lover, and not his brother, too. 

It was semantics-- the incest taboo had stopped featuring in his guilt years before.

"I was hardly worried, Sherlock. However, do remember to feed and water him sometimes. We don't need a repeat of the last one, and hiding bodies in London isn't as easy as you might think. Especially when you don't want them found right away."

Because if the bodies were discovered too quickly, Sherlock might be implicated. Or worse, wouldn't be able to solve the mystery of their disappearance. He always knew who killed them, that was the easy part-- but what happened after?

Mycroft was something of a virtuoso in arranging strange and intriguing corpse displays.

Sherlock's body was lean and comfortable as he rested back on his elbows, long legs crossed over Mycroft's lap. "John is different, but he's not smart enough to come to the right conclusions."

About the two of them, and their relationship. 

Their extra-curricular activities.

And Sherlock's penchant for finding out what colour people were on the inside. Sometimes you couldn't chase away the boredom without a little help, and a few unlucky Londoners were a small price to pay for keeping Mycroft's little brother happy.

Mycroft never got blood on his hands. But Sherlock enjoyed it. 

It fascinated him, the red warmth of it. The viscosity, and the smell of copper, and the way their eyes turned blank and glassy as it drained away.

"Now that you're finished your case, brother mine, does that mean you're willing to eat again?"

"I would. But you're probably going to suggest that horrible restaurant with the vegetarian dishes. I don't know why you gave up eating meat."

"Because it's unhealthy. And I plan to outlive you."

Mycroft smirked. But Sherlock's was darker, more amused by the idea, because they both knew that wasn't true. Mycroft had bruises from their good nights, and a few old, faded scars from the bad ones. If he was planning to outlive Sherlock, he should have fled years ago.

Mycroft Holmes had been running on borrowed time since he was seven, and his little brother was first set into his arms. He hadn't known the danger then, but the last thirty-six years had given him perspective.

"Liar... You won't eat meat because Hannibal Lecter is in jail, and when people ask you uncomfortable questions, you like having a ready excuse. You like their looks of relief when you tell them you couldn't be like him. A  _ cannibal _ . Because you don't consume flesh."

Sherlock rolled the word across his tongue with relish.  _ Cannibal _ . It was almost as filthy as  _ incest _ , or  _ murder _ , and much less common. 

Since Hannibal's arrest, it had made its way into everyday conversation, but Sherlock still enjoyed the dark weight of it on his tongue.

There was no point arguing that, they both knew it was true. Instead, Mycroft let his brother slide down into his lap, arms finding home around Sherlock's narrow waist. "You suffer no such complications, I'm sure. You delight in people being horrified at the idea. It's why you devour every newspaper and cheap magazine with his face on the cover."

"It's not every day a family friend is tried and convicted as a serial killer, Mycroft. I'm just showing the proper interest in his accomplishments."

"I suppose it takes one to know one."

Point to Mycroft, and Sherlock dipped his head to bite at his neck in retaliation. "If I'm such a monster, maybe I should eat you for dinner instead of your awful quinoa and soy steak."

"That sounds horrendous. You can eat whatever you like, brother mine." 

With an obliging tilt of his head, Mycroft bared his throat to his brother, letting him trace the lines of his veins with soft lips and sharp teeth. It sent the same low heat pooling in his belly, half hard under Sherlock's weight. 

He doubted they were going to make it out to dinner. Not when the bedroom was so conveniently located just down the hall. 

It was their anniversary, if they wanted to celebrate it in bed? It was nobody's business but their own.

Sherlock bit down, just to feel Mycroft tense, before pulling away to admire his handiwork. 

"That's going to be difficult to cover tomorrow, won't it?"

"That's the point, Mycie. You can indulge me, tonight is just about us."

"I already indulge you too much. I gave you a serial killer for a present."

"You  _ made _ me a serial killer. He wouldn't have come up with the idea of the suicide pills on his own." Still smiling, Sherlock rose to his feet and pulled his brother up from his leather desk chair. 

His body felt alight, even without the cocaine. He was buzzing, glowing, adrenaline still hot in his veins. 

Sherlock wanted to claim what was his, to leave reminders for Mycroft on every inch of his skin. Brands that said  _ Property of Sherlock Holmes. Touch at own risk. _

Not everyone listened to Sherlock's carefully branded warnings. Those idiots ended up in unfortunate places. But for tonight, it was just the two of them, and Sherlock was in a wonderful mood. 

No need for bloodshed-- from either of them-- when Mycroft was spoiling him so well.

Later that night, Sherlock propped himself on his elbow and watched his brother sleep. Mycroft looked peaceful, stretched out bare along the tangled sheets. He was a glorious canvas of dark bruises, and Sherlock traced the margins of them with his fingertips, making Mycroft shiver without waking.

He was helpless like this, and Sherlock had wanted to see the colours of his brother for years. He wanted to know what made him tick, and to hold his still-beating heart in the palms of his hands. 

Literally, instead of metaphorically.

They'd been holding each other metaphorically for years, finger over pulse. They read and deduced each other, and no matter what John Watson thought -- or any of the flatmates that had come before-- Sherlock and Mycroft understood one another intimately.

It wasn't anger, it was love. Sherlock loved his brother more than anything in the world-- and he wanted to know every secret piece of him. He wanted to own him, every molecule and cell, every drop of blood and scrap of muscle tissue.

There was a knife in his jacket pocket-- a useful tool when chasing down London's criminal element. A sleek, gleaming thing in chased silver, a birthday gift from Mycroft years before. 

But as usual, Sherlock didn't reach for it. 

For tonight, Mycroft was safe in his arms. 

And that was exactly how Sherlock wanted it.


End file.
